Increased pain sensitivity but normal function of exercise induced analgesia in hip and knee osteoarthritis--treatment effects of neuromuscular exercise and total joint replacement

Exercise therapy for knee osteoarthritis pain: how does it work? A study protocol for a randomised controlled trial

INTRODUCTION

Muscle strengthening training (MST) and behavioural graded activity (BGA) show comparable effects on knee osteoarthritic (KOA) pain, but the mechanisms of action remain unclear. Both exercise-induced anti-inflammation and central sensitisation are promising pathways for pain relief in response to exercise therapy in patients with KOA: MST has the potential to decrease inflammation and BGA has the potential to decrease central sensitisation. Hence, this study aims to examine inflammation and central sensitisation as mediators for the effect of MST and/or BGA on pain in patients with KOA.

METHODS AND ANALYSIS

The Knee OsteoArthritis PAIN trial started on 10 January 2020 (anticipated end: April 2024). The three-arm clinical trial aims to recruit 90 KOA patients who will be randomly allocated to 12 weeks of (1) MST, (2) BGA or (3) care as usual. Assessments will be performed at baseline, 13 and 52 weeks after finishing the intervention. Outcomes, including pain (Knee injury and Osteoarthritis Outcome Score), were chosen in line with the OARSI recommendations for clinical trials of rehabilitation interventions for OA and the IMMPACT/OMERACT recommendations for the assessment of physical function in chronic pain clinical trials. Inflammation as well as features of central sensitisation (including conditioned pain modulation, offset analgesia, temporal summation of pain and event-related potentials following electrical stimulation), will be considered as treatment mediators. A multiple mediators model will be estimated with a path-analysis using structural equation models. In July 2023, all 90 KOA patients have been included and 42 participants already finished the study.

ETHICS AND DISSEMINATION

This study obtained ethics approval (B.U.N. 143201941843). Unravelling the mechanisms of action of exercise therapy in KOA will not only be extremely valuable for researchers, but also for exercise immunology and pain scientists and clinicians.

TRIAL REGISTRATION NUMBER

NCT04362618.

Investigation of Reaction Time, Proprioception, and Shaped Pathway Walking Performance in Older Patients with Total Knee Arthroplasty

OBJECTIVES

The existing literature on total knee arthroplasty (TKA) does not provide clear data on step reaction time and proprioception and gait in shaped pathways. This study investigated the relationship between proprioception and reaction time with walking performance in shaped pathways in older patients undergoing TKA.

DESIGN

A cross-sectional observational study.

SETTING AND PARTICIPANTS

An orthopedic outpatient clinic with 103 older patients with TKA after a minimum of 6 months after surgery.

METHODS

Participants were evaluated with Figure-of-8 Walk Test (F8WT), L Test, Tinnetti Gait Test (TGT), proprioception measurement with an app-based inclinometer, and step reaction time (SRT) test. The same assessor carried out all evaluations.

RESULTS

F8WT showed a strong correlation with SRT-right, SRT-left, and Tinetti Gait Test (TGT), respectively (r1 = 0.628, r2 = 0.619, r3 = -0.615, P < .01). In addition, F8WT was moderately correlated with Right Leg Proprioception Test (RLPT) and Left Leg Proprioception Test (LLPT), respectively (r1 = 0.487, r2 = 0.439, P < .01). There was a moderate correlation between L Test with RLRT, LLRT, and TGT, respectively (r1 = 0.597, r2 = 0.584, r3 = -0.542, P < .01). Besides, there was a weak positive correlation between L Test with RLPT and LLPT, respectively (r1 = 0.394, r2 = 0.335, P < .01). A regression model showed that the L test was related to RLRT, LLRT, and TGT (R2 = 0.432, P < .001). The higher ability of the L test was weakly associated with higher levels of TGT (standardized β = -0.28, P = .0012). Besides, regression analysis also proved that F8WT was related to RLRT, LLRT, and TGT (R2 = 0.522, P < .001). The most highly associated parameter was LLRT (standardized β = 0.958, P = .003).

CONCLUSIONS AND IMPLICATIONS

Gait in shaped pathways is associated with proprioception, reaction time, and balance ability in older patients with TKA. Therefore, proprioception, reaction time, and balance should be considered to improve the shaped pathway walking performance of patients after bilateral, right, or left TKA surgery.

The effectiveness of aerobic versus strengthening exercise therapy in individuals with chronic whiplash-associated disorder: a randomised single case experimental design study

PURPOSE

Recent RCTs and meta-analyses compare the effectiveness of different types of exercise for chronic whiplash associated disorder (WAD). This study aimed to verify whether the results of these studies translate to statistically significant and clinically meaningful effects in individual participants.

MATERIALS AND METHODS

A series of replicated randomised single case experimental design studies (SCEDs) with A-B design (A: baseline, B: intervention). Eight participants with chronic WAD (8 female, mean [SD] age 47 [10] years) were randomised into one of four baseline durations (5, 8, 11, and 14 days) and to one of two eight-week exercise interventions (aerobic or strengthening). Daily measures of pain intensity, bothersomeness, and interference were collected during the baseline phase and the intervention phase.

RESULTS

Visual analyses indicated that three participants in the aerobic exercise group meaningfully improved. No improvements were found in the strengthening group. Effect sizes favoured the aerobic exercise group, yet randomisation tests of pooled effects did not show a difference in between-intervention effectiveness.

CONCLUSION

Contrary to our expectations, three out of four participants were nearly pain-free at the end of the aerobic exercise intervention, whereas none of the participants in the strengthening group improved meaningfully. This suggests that aerobic exercise may be favourable for WAD.Implications for RehabilitationOur results suggest that aerobic exercises are favourable over strengthening exercises and may be the preferred option for patients with chronic WAD.We found substantial variability in self-reported outcomes within participants, clinicians should be aware of this in the judgement of treatment effectiveness.

Three weeks of exercise therapy altered brain functional connectivity in fibromyalgia inpatients

Background

Fibromyalgia (FM) is a chronic pain syndrome characterized by widespread pain, tenderness, and fatigue. Patients with FM have no effective medication so far, and their activity of daily living and quality of life are remarkably impaired. Therefore, new therapeutic approaches are awaited. Recently, exercise therapy has been gathering much attention as a promising treatment for FM. However, the underlying mechanisms are not fully understood, particularly, in the central nervous system, including the brain. Therefore, we investigated functional connectivity changes and their relationship with clinical improvement in patients with FM after exercise therapy to investigate the underlying mechanisms in the brain using resting-state fMRI (rs-fMRI) and functional connectivity (FC) analysis.

Methods

Seventeen patients with FM participated in this study. They underwent a 3-week exercise therapy on in-patient basis and a 5-min rs-fMRI scan before and after the exercise therapy. We compared the FC strength of sensorimotor regions and the mesocortico-limbic system between two scans. We also performed a multiple regression analysis to examine the relationship between pre-post differences in FC strength and improvement of patients' clinical symptoms or motor abilities.

Results

Patients with FM showed significant improvement in clinical symptoms and motor abilities. They also showed a significant pre-post difference in FC of the anterior cingulate cortex and a significant correlation between pre-post FC changes and improvement of clinical symptoms and motor abilities. Although sensorimotor regions tended to be related to the improvement of general disease severity and depression, brain regions belonging to the mesocortico-limbic system tended to be related to the improvement of motor abilities.

Conclusion

Our 3-week exercise therapy could ameliorate clinical symptoms and motor abilities of patients with FM, and lead to FC changes in sensorimotor regions and brain regions belonging to the mesocortico-limbic system. Furthermore, these changes were related to improvement of clinical symptoms and motor abilities. Our findings suggest that, as predicted by previous animal studies, spontaneous brain activities modified by exercise therapy, including the mesocortico-limbic system, improve clinical symptoms in patients with FM.

Evolution of somatosensory processing signs after nociceptive targeted surgery in patients with musculoskeletal disorders: a systematic review

ABSTRACT

Surgery is often advised when conservative treatment fails in musculoskeletal pain conditions, but a substantial proportion still suffers chronic pain after surgery. Somatosensory processing system (SPS) signs were previously studied as potential predictors for chronic postsurgical pain, but results are inconsistent. Therefore, studying the evolution of SPS signs could be of added value. The aim was to summarize all studies that measured how SPS signs evolved after nociceptive targeted surgery in musculoskeletal disorders and to find preoperative, perioperative, and postoperative predictors for the evolution of these SPS signs. Data were summarized, and risk of bias and level of evidence and recommendation were determined. Twenty-one studies were included. Five scored a low, 3 a moderate, and 13 a high risk of bias. In general, no consistent evolution of SPS signs comparing preoperative and postoperative values and predictors for this evolution in musculoskeletal disorders could be found. In most cases, static quantitative sensory testing (QST) did not change or conflicting results were found. On the other hand, dynamic QST mostly improved after surgery. Worthfully mentioning is that worsening of SPS signs was only seen at a follow-up of <3 months after surgery, that conclusions are stronger when evaluating dynamic QST with a follow-up of ≥3 months after surgery, and that pain improvement postsurgery was an important predictor. Future high-quality research should focus on the evolution of SPS signs after nociceptive targeted surgery, accounting for pain improvement groups and focusing on preoperative, perioperative, and postoperative predictors of this evolution.

The autonomic and nociceptive response to acute exercise is impaired in people with knee osteoarthritis

Objectives

An acute bout of exercise typically leads to short term exercise induced hypoalgesia (EIH), but this response is more variable in many chronic pain populations, including knee osteoarthritis (OA) and fibromyalgia (FM). There is evidence of autonomic nervous system (ANS) dysfunction in some chronic pain populations that may contribute to impaired EIH, but this has not been investigated in people with knee OA. The aim of this study was to assess the acute effects of isometric exercise on the nociceptive and autonomic nervous systems in people with knee OA and FM, compared to pain-free controls.

Methods

A cross-sectional study was undertaken with 14 people with knee OA, 13 people with FM, and 15 pain free controls. Across two experimental sessions, baseline recordings and the response of the nociceptive and autonomic nervous systems to a 5-min submaximal isometric contraction of the quadriceps muscle was assessed. The nociceptive system was assessed using pressure pain thresholds at the knee and forearm. The ANS was assessed using high frequency heart rate variability, cardiac pre-ejection period, and electrodermal activity. Outcome measures were obtained before and during (ANS) or immediately after (nociceptive) the acute bout of exercise.

Results

Submaximal isometric exercise led to EIH in the control group. EIH was absent in both chronic pain groups. Both chronic pain groups showed lower vagal activity at rest. Furthermore, people with knee OA demonstrated reduced vagal withdrawal in response to acute isometric exercise compared to controls. Sympathetic reactivity was similar across groups.

Discussion

The findings of reduced tonic vagal activity and reduced autonomic modulation in response to isometric exercise raise the potential of a blunted ability to adapt to acute exercise stress and modulate nociception in people with knee OA. The impairment of EIH in knee OA may, in part, be due to ANS dysfunction.

The effects of a 15-week physical exercise intervention on pain modulation in fibromyalgia: Increased pain-related processing within the cortico-striatal- occipital networks, but no improvement of exercise-induced hypoalgesia

Dysfunctional top-down pain modulation is a hallmark of fibromyalgia (FM) and physical exercise is a cornerstone in FM treatment. The aim of this study was to explore the effects of a 15-week intervention of strengthening exercises, twice per week, supervised by a physiotherapist, on exercise-induced hypoalgesia (EIH) and cerebral pain processing in FM patients and healthy controls (HC). FM patients (n = 59) and HC (n = 39) who completed the exercise intervention as part of a multicenter study were examined at baseline and following the intervention. Following the exercise intervention, FM patients reported a reduction of pain intensity, fibromyalgia severity and depression. Reduced EIH was seen in FM patients compared to HC at baseline and no improvement of EIH was seen following the 15-week resistance exercise intervention in either group. Furthermore, a subsample (Stockholm site: FM n = 18; HC n = 19) was also examined with functional magnetic resonance imaging (fMRI) during subjectively calibrated thumbnail pressure pain stimulations at baseline and following intervention. A significant main effect of exercise (post > pre) was observed both in FM patients and HC, in pain-related brain activation within left dorsolateral prefrontal cortex and caudate, as well as increased functional connectivity between caudate and occipital lobe bordering cerebellum (driven by the FM patients). In conclusion, the results indicate that 15-week resistance exercise affect pain-related processing within the cortico-striatal-occipital networks (involved in motor control and cognition), rather than directly influencing top-down descending pain inhibition. In alignment with this, exercise-induced hypoalgesia remained unaltered.

Training-induced hypoalgesia and its potential underlying mechanisms

It is well-established that a single bout of exercise can reduce pain sensitivity (i.e., exercise-induced hypoalgesia) in healthy individuals. However, exercise-induced hypoalgesia is often impaired in individuals with chronic pain. This might suggest that repeated bouts of exercise (i.e., exercise training) are needed in order to induce a reduction in pain sensitivity (i.e., training-induced hypoalgesia) among individuals with chronic pain, given that a single bout of exercise seems to be insufficient to alter pain. However, the effect of repeated bouts of exercise on pain sensitivity and its underlying mechanisms remain poorly understood. Therefore, the purpose of this review was to provide an overview of the existing literature on training-induced hypoalgesia, as well as discuss potential mechanisms of training-induced hypoalgesia and offer considerations for future research. Existing literature suggests that training interventions may induce hypoalgesic adaptations potentially driven by central nervous system and immune system factors. However, the limited number of randomized controlled trials available, along with the lack of understanding of underlying mechanisms, provides a rationale for future research.

Effect of Neuromuscular Electrical Stimulation During Walking on Pain Sensitivity in Women With Obesity With Knee Pain: A Randomized Controlled Trial

OBJECTIVE

To assess the extent to which pain sensitivity is altered in women with obesity with frequent knee symptoms who walk with either a hybrid training system (HTS) that provides antagonist muscle electrical stimulation vs sensory transcutaneous electrical nerve stimulation (TENS).

DESIGN

Randomized, double-blinded, controlled trial.

SETTING

University-based fitness center.

PARTICIPANTS

Twenty-eight women (N=28) with obesity, aged 40-70 years, with daily knee symptoms.

INTERVENTIONS

Participants were randomized to 12 weeks of biweekly 30-minute walking exercise with either HTS (HTSW group) or sensory TENS (control group).

MAIN OUTCOME MEASURES

Pressure pain thresholds (PPTs) at the more symptomatic knee (local PPT) and PPT at the ipsilateral pain-free wrist (remote PPT).

RESULTS

After adjustment for preintervention values and body mass index (BMI), there was a statistically significant improvement in local PPT in the HTSW group compared with the control group (P=.039). After adjustment for pretraining value, age, and BMI, changes in remote PPT when comparing groups did not reach statistical significance, although the HTS group tended to demonstrate increased remote PPT (P=.052) compared with the control group. Moreover, after adjustment for pretraining value, knee pain, and quality of life, comparing groups did not reach statistical significance, although the HTS group tended to demonstrate decreased knee pain (P=.069) compared with the control group.

CONCLUSIONS

Augmentation of walking exercise with HTS was more effective than application of sensory TENS in improving local pain sensitivity at the knee but not at the wrist in women with obesity with frequent knee symptoms.

Pain's Adverse Impact on Training-Induced Performance and Neuroplasticity: A Systematic Review

Motor training is a widely used therapy in many pain conditions. The brain’s capacity to undergo functional and structural changes i.e., neuroplasticity is fundamental to training-induced motor improvement and can be assessed by transcranial magnetic stimulation (TMS). The aim was to investigate the impact of pain on training-induced motor performance and neuroplasticity assessed by TMS. The review was carried out in accordance with the PRISMA-guidelines and a Prospero protocol (CRD42020168487). An electronic search in PubMed, Web of Science and Cochrane until December 13, 2019, identified studies focused on training-induced neuroplasticity in the presence of experimentally-induced pain, 'acute pain' or in a chronic pain condition, 'chronic pain'. Included studies were assessed by two authors for methodological quality using the TMS Quality checklist, and for risk of bias using the Newcastle–Ottawa Scale. The literature search identified 231 studies. After removal of 71 duplicates, 160 abstracts were screened, and 24 articles were reviewed in full text. Of these, 17 studies on acute pain (n = 7) or chronic pain (n = 10), including a total of 258 patients with different pain conditions and 248 healthy participants met the inclusion criteria. The most common types of motor training were different finger tasks (n = 6). Motor training was associated with motor cortex functional neuroplasticity and six of seven acute pain studies and five of ten chronic pain studies showed that, compared to controls, pain can impede such trainings-induced neuroplasticity. These findings may have implications for motor learning and performance and with putative impact on rehabilitative procedures such as physiotherapy.

Hypoalgesia following isometric handgrip exercise with and without blood flow restriction is not mediated by discomfort nor changes in systolic blood pressure

The purpose was to examine the effect of isometric handgrip exercise with and without blood flow restriction on exercise-induced hypoalgesia at a local and non-local site, and its underlying mechanisms. Sixty participants (21 males & 39 females, 18-35 years old) completed 3 trials: four sets of 2-minute isometric handgrip exercise at 30% of maximum handgrip strength; isometric handgrip exercise with blood flow restriction at 50% of arterial occlusion pressure; and a non-exercise time-matched control. Pain thresholds increased similarly in both exercise conditions at a local (exercise conditions: ~0.45 kg/cm², control: ~-0.04 kg/cm²) and non-local site (exercise conditions: ~0.37 kg/cm², control: ~-0.16 kg/cm²). Blood flow restriction induced greater feelings of discomfort compared to exercise alone [median difference (95% credible interval) of 4.5 (0.5, 8.6) arbitrary units]. Blood pressure increased immediately after exercise (systolic: 10.3 mmHg, diastolic: 7.7 mmHg) and decreased in recovery. There was no within participant correlation between changes in discomfort and pressure pain threshold. A bout of isometric handgrip exercise with or without blood flow restriction can provide exercise-induced hypoalgesia at a local and non-local site. However, discomfort and changes in systolic blood pressure do not explain this response.

Exercise induced hypoalgesia profile in rats is associated with IL-10 and IL-1 β levels and pain severity following nerve injury

BACKGROUND

Pain may undergo modulation in the central nervous system prior to reaching the primary somatosensory cortex and being perceived as pain. Faulty pain modulation mechanisms have been linked to various chronic pain conditions. Cytokines such as IL-10 and IL-1beta, are known to be involved in initiation and maintenance of neuropathic pain. In this study, we investigated the association between pain modulation profile, pain intensity and cytokines (IL-10 and IL-1beta) levels in a rat model of neuropathic pain.

METHODS

Exercise-Induced Hypoalgesia (EIH) was assessed by evaluating the percentage of responses to a train of 60g mechanical stimuli before and after 180 seconds of exercise on a rotating rod. The differences in the response rates before and after the exercise were used to divide the rats into low and high EIH responders. Rats from low and high EIH groups underwent constriction injury of the left sciatic nerve. Pain behavior (allodynia and hyperalgesia) were assessed by measuring responses to mechanical and thermal stimuli applied to the plantar surface of the foot. Serum, sciatic nerve and the related Dorsal Root Ganglia (DRG) levels of IL-10 and IL-1beta were determined by ELISA. The DRG mRNA levels of IL-10 and IL-1beta measured with PCR. A comparison between the low and high EIH rats of all measured parameters was made.

RESULTS

The low EIH rats developed significantly more severe allodynia and hyperalgesia in the affected paw and allodynia in the contralateral paw compared to the high EIH rats, 7 days following the injury. The low EIH rats had higher IL-1beta protein levels in serum prior to and following injury, higher affected and contralateral sciatic nerve IL-1beta levels following injury and higher IL-1beta levels in the contralateral DRG (protein and mRNA) following injury when compared to high EIH rats. The high EIH rats had higher affected sciatic nerve IL-10 levels following nerve injury and higher IL-10 levels of both protein and mRNA in the affected and contralateral DRG at baseline and following injury.

CONCLUSION

EIH profile was found to be predictive of pain behavior following nerve injury, low EIH rats developed more severe allodynia and hyperalgesia. IL-1beta may be associated with painful neuropathy developed in rats with low EIH while the anti-inflammatory cytokine IL-10 may have a protective role, inhibiting the development of painful.

Changes in prefrontal cortex activation with exercise in knee osteoarthritis patients with chronic pain: An fNIRS study

The role of exercise on pain modulatory mechanism of the prefrontal areas is not clear. We aimed to determine the effects of exercise on functional activity of the prefrontal cortex in patients with knee osteoarthritis (OA) with chronic pain and to assess the relationships between changes in clinical variables and cortical hemodynamics with exercise via functional near-infrared spectroscopy (fNIRS). Fifteen patients with knee OA with chronic pain were included. All participants attended an exercise program 3 times a week for 6 weeks. Pain during activity was assessed by visual analogue scale (VAS). Pain catastrophization, kinesiophobia and functionality were also measured. Brain hemodynamic activity was assessed with a 47-channel fNIRS system before and after the exercise. Pain, pain catastrophization, kinesiophobia and functionality scores significantly improved (p < 0.05) while functional activity of the dorsolateral prefrontal cortex (DLPFC) during painful stimuli was significantly reduced after exercise program (p < 0.05). Change in cortical hemodynamic activity within the DLPFC was significantly correlated with change in pain perception (R = 0.54, p < 0.05) and pain catastrophization scores (R = 0.44, p < 0.05). Exercise resulted in improvements in clinical assessments of pain severity and pain catastrophization which was accompanied by alterations in prefrontal cortex activation. We provided evidence about the pain modulatory effects of exercise at cortical level which is correlated with clinical improvements in patients with chronic pain. We demonstrate the feasibility and potential of fNIRS methodology for i) elucidating the neural mechanisms underlying chronic and stimulus evoked pain, and ii) exploring the effect of treatment methods on brain functionality.

A probiotic intervention on pain hypersensitivity and microbiota composition in patients with osteoarthritis pain: Study protocol for a randomized controlled trial

OBJECTIVES

This study aims to examine the effects of probiotics on pain hypersensitivity at the end of a six-week intervention program in patients with osteoarthritis (OA)-related pain.

PATIENTS AND METHODS

This double-blind randomized controlled clinical trial with two parallel arms will be conducted between January 2021 and July 2022. At least 30 participants (age range, 50 to 90 years) of both sexes with a diagnosis of symptomatic hip or knee (Kellgren-Lawrence scale ≥3) will be recruited in each arm (total n=60) to achieve adequate statistical power in the analyses. The intervention will be administered for six weeks followed by a four-week follow-up period. The experimental group will receive a probiotic product plus the usual medical care. The control group will receive a probiotical sham plus the usual medical care. Assessment points will be measured at baseline, end of intervention, and one-month post-intervention. The outcomes of this intervention will be a change in visual analog scale pain and the gut microbiota composition. Group by time effects will be compared using mixed-model analysis of variance.

CONCLUSION

A reduction in pain hypersensitivity in patients with knee OA-related pain could suggest an involvement of microbiota, or part of it, in chronic pain state mechanisms.

Sensorimotor training prior total knee arthroplasty and effects on functional outcome: A systematic review and meta-analysis

BACKGROUND

Altered muscle activation patterns and proprioception, loss of strength, and weight bearing asymmetries are common limitations after total knee arthroplasty, which can also affect balance. Therefore, preoperative sensorimotor training has been proposed to enhance surgical outcome.

RESEARCH QUESTION

Is preoperative sensorimotor training effective in improving functional outcome in patients undergoing total knee arthroplasty? Does preoperative sensorimotor training affect secondary outcomes such as balance, pain, and quality of life?

METHODS

A systematic review and meta-analysis were conducted by searching PEDro, MEDLINE, Embase, Cochrane Library, and Scopus databases from inception to May 2020. Studies were eligible if participants underwent total knee arthroplasty after two or more weeks of preoperative sensorimotor training. A meta-analysis compared the effects of such interventions with standard care before and after surgery using standardized mean differences (SMD) with 95 % confidence interval (CI). Functional outcome was the primary measure. Balance, pain, and quality of life were also outcomes of interest.

RESULTS

Of the 384 items identified, 7 met the inclusion criteria, and 332 participants were assessed. There was limited evidence suggesting that preoperative sensorimotor training enhanced self-reported function (SMD, 0.89; 95 % CI, 0.16-1.62), functional performance (SMD, 0.56; 95 % CI, 0.19 to 0.93), or knee function (SMD = 0.22-1.05) compared with conventional care. Moderate quality evidence suggested that benefits were only maintained in terms of functional performance up to 3 months after surgery (SMD = 0.37; 95 % CI, 0.13 to 0.62). The outcome was similar after one year.

SIGNIFICANCE

Compared with conventional care, preoperative sensorimotor training may enhance early postoperative functional recovery, with no additional benefits on balance, knee function, or pain. The outcome is the same one year after surgery, regardless of whether such training is implemented. Further investigation is needed to determine whether sensorimotor training may be a feasible conservative treatment for severe knee osteoarthritis.

Exercise-induced hypoalgesia and pain reduction following blood flow restriction: A brief review

OBJECTIVE

To review past literature regarding exercise-induced hypoalgesia and pain reduction following blood flow restriction interventions, and to discuss potential mechanisms as well as future considerations towards the efficacy of blood flow restriction in pain reduction following exercise.

METHODS

To be eligible for inclusion, studies had to include acute exercise, or long-term training interventions, with blood flow restriction, along with including pre and post intervention pain measurements.

RESULTS

A total of 13 studies met the inclusion criteria. Among these 13 studies, 3 studies examined exercise-induced hypoalgesia after an acute bout of resistance exercise with blood flow restriction, and 10 studies investigated pain reduction following long-term blood flow restriction training.

CONCLUSIONS

Existing literature suggests that low load resistance exercise with blood flow restriction may serve as an effective pain management method for those who are unable or unwilling to train with high loads. Several potential mechanisms have been suggested, however, the roles of these mechanisms are still unclear and require further clarification. Future research should consider implementing different methods of blood flow restriction application, and research study design to clarify the utility and efficacy of blood flow restriction as a pain management tool, by itself or in combination with exercise.

Modulation of Exercise-Induced Hypoalgesia Following an Exercise Intervention in Healthy Subjects

BACKGROUND

Exercise is recommended to promote and maintain health and as treatment for more than 25 diseases and pain conditions. Exercise-induced hypoalgesia (EIH), a measure of descending pain inhibitory control, has been found to be impaired in some chronic pain conditions, but it is currently unclear if EIH is modifiable. This study investigated whether a long-term exercise intervention could modulate EIH in healthy subjects.

METHODS

In 38 healthy subjects, EIH was assessed as change in pressure pain threshold (PPT) after a three-minute isometric wall squat within the first week and after approximately seven weeks of military training (MT). Further, temporal summation of pain (TSP) and Knee injury and Osteoarthritis Outcome Score (KOOS) were assessed. Physical performance capacity was assessed using the Endurance 20-m shuttle run fitness test (20MSR). Hypoalgesic (EIH > 0.0 kPa) and hyperalgesic (EIH ≤ 0.0 kPa) subgroups were defined based on baseline EIH. Change in EIH following MT was used as the primary outcome.

RESULTS

Increased EIH (P = 0.008), PPT (P < 0.003), and 20MSR (P < 0.001) were found following MT, with no changes in TSP and KOOS (P > 0.05). Subjects with a hyperalgesic EIH response at baseline (26% of the participants) presented significantly improved EIH following MT (P = 0.010). Finally, an association between 20MRS change and EIH change was found (r = 0.369, P = 0.023).

CONCLUSIONS

MT increased EIH, especially in subjects who demonstrated a hyperalgesic response at baseline. Improvement in physical performance capacity was associated with an improvement in EIH, indicating that improvement in physical performance capacity may improve central pain mechanisms.

Effect of exercise on pain processing and motor output in people with knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

Guidelines recommend exercise as a core treatment for knee osteoarthritis. However, it is unclear how exercise affects measures of pain processing and motor function. The aim was to evaluate the effect of exercise on measures of pain processing and motor function in people with knee osteoarthritis.

METHODS

We searched five electronic databases (MEDLINE, EMBASE, CINAHL, SCOPUS and Cochrane Central Register of Controlled Trials) for studies on knee osteoarthritis, of any design, evaluating pain processing and motor function before and after exercise. Data were pooled with random-effects meta-analysis. Study quality was assessed using the Downs and Black and quality of evidence was assessed using the GRADE.

RESULTS

Eighteen studies were eligible and 16 were included. Following acute exercise, pressure pain threshold increased local to the study limb (standardised mean difference [95% confidence interval (CI)] 0.26, [0.02, 0.51], n = 159 from 5 studies), but there was no statistically significant change remote from the study limb (0.09, [-0.11, 0.29], n = 90 from 4 studies). Following an exercise program (range 5-12 weeks) there were no statistically significant changes in pressure pain threshold (local 0.23, [-0.01, 0.47], n = 218 from 8 studies; remote 0.33 [-0.13, 0.79], n = 76 from 4 studies), temporal pain summation (0.38 [-0.08, 0.85], n = 122 from 3 studies) or voluntary quadriceps muscle activation (4.23% [-1.84 to 10.30], n = 139 from 4 studies).

CONCLUSION

Very-low quality evidence suggests that pressure pain threshold increases following acute exercise. Very-low quality evidence suggests that pressure pain threshold, temporal pain summation or voluntary quadriceps activation do not change statistically significantly following exercise programs.

Short term relief of multisite chronicpain with Bowen Therapy: A double-blind, randomized controlled trial

INTRODUCTION

Bowen Therapy, a form of soft tissue manipulation, is commonly used to treat musculoskeletal conditions; yet, there is little evidence for its efficacy. The goal of the study was to investigate the impact of Bowen Therapy on pain and function in people with chronic pain in multiple locations. Additionally, we examined the mechanisms of effect through monitoring the nociceptive and autonomic nervous systems.

METHOD

The study was a double-blind, randomized controlled trial involving 31 people with chronic pain. Participants were randomized into real and sham therapy groups. Each group received 6 sessions of therapy over 8 weeks. The primary outcome measures of pain and function were assessed using standard questionnaires. Quantitative sensory testing was used to assess the nociceptive system, while recordings of heart rate variability and skin conductance were used to assess the autonomic nervous system. Outcome measures were assessed at baseline and at 1- and 6-weeks following completion of the intervention.

RESULTS

The real therapy group had a significantly lower pain score 1-week following the intervention compared to the sham group. There were no differences between groups at the final follow-up or in the function measures. There was no significant change in the nociceptive measures but there was evidence of increased activation of the sympathetic nervous system.

DISCUSSION

Bowen Therapy gave rise to a short-term reduction in pain that was not evident in a sham therapy group. The mechanisms of action of Bowen Therapy remain uncertain but may involve sympathoexcitation.

Efficacy of proprioceptive training on the recovery of total joint arthroplasty patients: a meta-analysis

BACKGROUND

Optimal balance control is of paramount importance for function recovery after total joint arthroplasty (TJA). The study objective of this meta-analysis was to assess the short- and mid-term effects of proprioceptive and balance training for patients undergoing TJA.

METHODS

Electronic searches were conducted from PubMed, Cochrane library, and Embase databases to identify eligible RCTs through May 2020. Standard mean difference (SMD) with 95% confidence interval (95%CI) was applied to calculate pooled effect estimates between proprioceptive and balance training and control group. Main outcomes were self-reported functionality, balance, pain, quality of life, and function (range of motion).

RESULTS

Seven randomized controlled trials were finally included in this meta-analysis. Pooled results found that balance and proprioceptive trainings have a positive role in improving self-reported functionality at short-term after TJA. Moreover, balance and proprioceptive trainings were associated with an increase of the balance at short- and mid-term after TJA. These results were further confirmed by subgroup analysis between preoperative and postoperative administration of balance and proprioceptive trainings.

CONCLUSION

Our meta-analysis suggests that balance and proprioceptive trainings after TJA improved self-reported functionality and balance. These improvements were maintained at mid-terms. More research is needed to confirm balance and proprioceptive trainings for pain and quality of life for TJA.

A Higher Grey Matter Density in the Amygdala and Midbrain Is Associated with Persistent Pain Following Total Knee Arthroplasty

Objective

The development of persistent pain following total knee arthroplasty (TKA) is common, but its underlying mechanisms are unknown. The goal of the study was to assess brain grey matter structure and its correlation with function of the nociceptive system in people with good and poor outcomes following TKA.

Subjects

Thirty-one people with LOW_PAIN (&lt;3/10 on the numerical ratings scale [NRS]) at six months following TKA and 15 people with HIGH_PAIN (≥3/10 on the NRS) were recruited into the study.

Methods

Grey matter in key brain areas related to nociception was analyzed using voxel-based morphometry (VBM). Nociceptive facilitatory and inhibitory processes were evaluated using quantitative sensory testing (QST). QST scores and grey matter density in prespecified brain regions were compared between the LOW_PAIN and HIGH_PAIN groups. Regression analyses were used to analyze the associations between the grey matter and QST scores.

Results

There were no between-group differences in QST measures. In the VBM analysis, the HIGH_PAIN group had a higher grey matter density in the right amygdala, right nucleus accumbens, and in the periaqueductal grey (PAG), but lower grey matter density in the dorsal part of the left caudate nucleus. Grey matter density in the right amygdala and PAG correlated positively with temporal summation of pain.

Conclusions

Persistent pain at six months after TKA is associated with a higher grey matter density in the regions involved in central sensitization and pain-related fear, which may contribute to the development of persistent pain after surgery.

Exercise-induced hypoalgesia after acute and regular exercise: experimental and clinical manifestations and possible mechanisms in individuals with and without pain

This review describes methodology used in the assessment of the manifestations of exercise-induced hypoalgesia in humans and previous findings in individuals with and without pain. Possible mechanisms and future directions are discussed.

Exercise and physical activity is recommended treatment for a wide range of chronic pain conditions. In addition to several well-documented effects on physical and mental health, 8 to 12 weeks of exercise therapy can induce clinically relevant reductions in pain. However, exercise can also induce hypoalgesia after as little as 1 session, which is commonly referred to as exercise-induced hypoalgesia (EIH). In this review, we give a brief introduction to the methodology used in the assessment of EIH in humans followed by an overview of the findings from previous experimental studies investigating the pain response after acute and regular exercise in pain-free individuals and in individuals with different chronic pain conditions. Finally, we discuss potential mechanisms underlying the change in pain after exercise in pain-free individuals and in individuals with different chronic pain conditions, and how this may have implications for clinical exercise prescription as well as for future studies on EIH.

Pain, sensitization and physical performances in patients with chronic painful knee osteoarthritis or chronic pain following total knee arthroplasty: An explorative study

BACKGROUND

The aim of this study was to assess clinical pain, pain sensitization and physical performances to profile patients with chronic painful knee osteoarthritis (OA) or pain after total knee arthroplasty (TKA). Examining the interactions between pain mechanisms and physical performances would enable us to investigate the underlying explanatory relationships between these parameters.

METHODS

In this explorative study, 70 patients with chronic painful knee OA (N = 46) or chronic pain after TKA (N = 24) were assessed for clinical pain, quantitative sensory profiling (mechanical pinprick pain sensitivity, temporal summation (TS) and conditioned pain modulation), physical performances (chair stand, walk and stair climb tests) and self-reported outcomes. Between-group comparisons were made using ANCOVA tests and associations between outcomes were analysed using multivariate linear regression models.

RESULTS

Overall, no differences between groups regarding clinical pain and quantitative sensory profiling outcomes were observed. Physical performances were lower in the TKA group compared with the OA group with moderate-to-large effect sizes, and a tendency towards better scores in self-reported outcomes for the OA group was observed with small-to-moderate effect sizes. Self-reported function seems to be associated with physical performances in the TKA group. Sensitization (TS) appears to be associated with poorer physical performances in the OA group.

CONCLUSIONS

Similar profiles for pain intensity, signs of sensitization and conditioned pain modulation were observed. Patients with TKA seems to have impaired physical performances compared with the OA group, underlining the importance of targeting physical performances. Only the OA patients showed an association between sensitization (TS) and physical performance.

SIGNIFICANCE

Quantitative pain profiling assessment was used to assess pain intensities and pain mechanisms. We observed associations between physical performances and temporal summation in the OA group underlining the importance of assessing motor functions and pain mechanisms in the same trial. We observed lower levels of physical performances in the TKA group compared with the OA group, suggesting that examination and rehabilitation of physical performances is essential for TKA patients with chronic pain.

Short-term Effects of Mulligan's Mobilization With Movement on Pain, Function, and Emotional Aspects in Individuals With Knee Osteoarthritis: A Prospective Case Series

OBJECTIVE

To evaluate the short-term effects of Mulligan's mobilization with movement (MWM) on pain, physical function, emotional aspects, and proprioceptive acuity after a 2-week treatment period and throughout a 3-week follow-up period.

METHODS

A single group of 30 participants (60.96 ± 5.16 years) with symptomatic knee osteoarthritis (KOA) was evaluated. The protocol involved 5 evaluations moments, before (baseline) and after 2 weeks of intervention (24 hours after the last session), and at 3-week follow-up. The intervention included 3 Mulligan's MWM techniques. The variables evaluated were pain (pressure pain threshold and Visual Numeric Scale), physical function (range of motion, proprioceptive acuity, and the Western Ontario and McMaster Universities Osteoarthritis Index) and emotional aspects (Beck Depression Inventory). Analysis of variance for repeated measures was used considering a significance level of 5%.

RESULTS

At the second evaluation (after intervention), the pressure pain threshold presented higher values for rectus femoris, tibialis anterior, and patellar tendon sites and reduced values for the Visual Numeric Scale, Beck Depression Inventory, and Western Ontario and McMaster Universities Osteoarthritis Index compared with baseline. Also, during the follow-up period, all variables returned close to baseline levels. Proprioceptive acuity and range of motion did not present significant changes.

CONCLUSION

Scores for pain relief, physical function, and emotional aspects improved after a course of MWM in this single group of individuals with KOA. Mobilization with movement had limited outcome during follow-up. It suggests that future clinical trials on the use of MWM for KOA should be considered.

The Relationship Between Daily Physical Activity and Pain in Individuals with Knee Osteoarthritis

Objective

Investigate the association between physical activity and pain severity in individuals with knee osteoarthritis.

Design

Cross-sectional; systematic review with meta-analyses.

Methods

Thirty-one participants with knee osteoarthritis underwent assessment of symptoms via self-report questionnaires and quantitative sensory testing. Following testing, physical activity and symptoms were monitored for seven days using accelerometers and logbooks. Cross-correlation analyses were performed on fluctuations in symptoms and physical activity across the week to detect the relative timing of the strongest association between pain and activity. These data were complemented by meta-analyses of studies that examined correlations between pain from knee osteoarthritis and physical activity or fitness.

Results

Pain severity at baseline correlated with moderate to vigorous physical activity (r2 = 0.161–0.212, P &lt; 0.05), whereby participants who were more physically active had less pain. Conversely, the peak of the cross-correlation analyses was most often positive and lagging, which indicated that pain was increased subsequent to periods of increased activity. These superficially discrepant findings were supported by the results of a meta-analysis of 13 studies and 9,363 participants, which identified significant heterogeneity for associations between physical activity and pain (I2 = 91%). Stronger inverse associations were found between fitness and pain.

Conclusions

Associations between physical activity and pain in people with knee osteoarthritis are variable and dynamic. These results reflect the beneficial impact of an active lifestyle and accompanying higher fitness. Yet, the side effect of acute periods of physical activity to transiently exacerbate pain may influence the behavior of some people to avoid activity because of pain.

Structural Brain Alterations Before and After Total Knee Arthroplasty: A Longitudinal Assessment

Objective

Many studies have provided evidence of altered brain structure in chronic pain conditions, as well as further adaptations following treatment that are coincident with changes in pain. Less is known regarding how these structural brain adaptations relate to assessments of nociceptive processing. The current study aimed to investigate brain structure in people with knee osteoarthritis (OA) before and after total knee arthroplasty (TKA) and to investigate the relationships between these findings and quantitative sensory testing (QST) of the nociceptive system.

Methods

Twenty-nine people with knee OA underwent magnetic resonance imaging (MRI) scans and QST before and six months after TKA and were compared with a pain-free control group (N = 18). MRI analyses involved voxel-based morphometry and fractional anisotropy.

Results

Before TKA, there was reduced gray matter volume and impaired fractional anisotropy in areas associated with nociceptive processing, with further gray matter adaptations and improvements in fractional anisotropy evident after TKA. QST revealed increased nociceptive facilitation and impaired inhibition in knee OA that was reversed after TKA. There were minimal relationships found between MRI data and QST assessments or pain report.

Conclusions

In people with end-stage knee OA, region-specific gray matter atrophy was detected, with further changes in gray matter volume and improvements in white matter integrity observed after joint replacement. Despite coincident alterations in nociceptive inhibition and facilitation processes, there did not appear to be any association between these functional assessments of the nociceptive system and changes in brain structure.

Exercise-Induced Hypoalgesia in Pain-Free and Chronic Pain Populations: State of the Art and Future Directions

Exercise is considered an important component of effective chronic pain management and it is well-established that long-term exercise training provides pain relief. In healthy, pain-free populations, a single bout of aerobic or resistance exercise typically leads to exercise-induced hypoalgesia (EIH), a generalized reduction in pain and pain sensitivity that occurs during exercise and for some time afterward. In contrast, EIH is more variable in chronic pain populations and is more frequently impaired; with pain and pain sensitivity decreasing, remaining unchanged or, in some cases, even increasing in response to exercise. Pain exacerbation with exercise may be a major barrier to adherence, precipitating a cycle of physical inactivity that can lead to long-term worsening of both pain and disability. To optimize the therapeutic benefits of exercise, it is important to understand how EIH works, why it may be impaired in some people with chronic pain, and how this should be addressed in clinical practice. In this article, we provide an overview of EIH across different chronic pain conditions. We discuss possible biological mechanisms of EIH and the potential influence of sex and psychosocial factors, both in pain-free adults and, where possible, in individuals with chronic pain. The clinical implications of impaired EIH are discussed and recommendations are made for future research, including further exploration of individual differences in EIH, the relationship between exercise dose and EIH, the efficacy of combined treatments and the use of alternative measures to quantify EIH. PERSPECTIVE: This article provides a contemporary review of the acute effects of exercise on pain and pain sensitivity, including in people with chronic pain conditions. Existing findings are critically reviewed, clinical implications are discussed, and recommendations are offered for future research.

Long-term, health-enhancing physical activity is associated with reduction of pain but not pain sensitivity or improved exercise-induced hypoalgesia in persons with rheumatoid arthritis

Background

We aimed to evaluate the 1-year and 2-year outcome of a health-enhancing physical activity (HEPA) support program on global pain, pressure pain sensitivity, and exercise-induced segmental and plurisegmental hypoalgesia (EIH) in persons with rheumatoid arthritis (RA).

Methods

Thirty participants (27 women and 3 men) were recruited from a larger intervention cohort that engaged in strength training and moderate-intensity aerobic activity. Assessments were performed before the HEPA intervention and at 1-year and 2-year follow-ups. Global pain was assessed on a visual analogue scale (0–100). Pressure pain thresholds (PPTs) and suprathreshold pressure pain at rest corresponding to 4/10 (medium pain) (SP4) and 7/10 (strong pain) (SP7) on Borg CR 10 scale were assessed by algometry. In a subsample (n = 21), segmental and plurisegmental EIH were assessed during standardized submaximal static contraction (30% of the individual maximum), by algometry, alternately at the contracting right M. quadriceps and the resting left M. deltoideus.

Results

Global pain decreased from before the intervention to 2-year follow-up (median 11 to median 6, P = 0.040). PPTs and SP4 pressure pain at rest did not change from before the intervention to 2-year follow-up, while SP7 decreased from mean 647 kPa to mean 560 kPa (P = 0.006). Segmental EIH during static muscle contraction increased from the assessment before the intervention (from mean 1.02 to mean 1.42, P = 0.001), as did plurisegmental EIH (from mean 0.87 to mean 1.41, P <0.001). There were no statistically significant changes in segmental or plurisegmental EIH from before the intervention to 2-year follow-up.

Conclusion

Participation in a long-term HEPA support program was associated with reduced global pain, whereas pressure pain sensitivity at rest was not reduced and EIH did not change. Thus, our results do not favor the hypothesis that long-term HEPA reduces pain by improving descending pain inhibition in persons with RA.

Trial registration

ISRCTN25539102, ISRCTN registry, date assigned March 4, 2011. The trial was retrospectively registered.

Effects of balance and proprioceptive training on total hip and knee replacement rehabilitation: A systematic review and meta-analysis

BACKGOUND

Balance and proprioceptive deficits are frequently persistent after total joint replacement, limiting functionality and involving altered movement patterns and difficulties in walking and maintaining postural control among patients.

RESEARCH QUESTION

The goal of this systematic review was to evaluate the short- and mid-term effects of proprioceptive and balance training for patients undergoing total knee and hip replacement.

METHODS

This is a systematic review of literature. MEDLINE, Embase, Cochrane Library, PEDro, and Scopus were the databases searched. The review included randomized clinical trials in which the experimental groups underwent a training aimed at improving balance and proprioception, in addition to conventional care. The studies had to assess at least one of the following outcomes: self-reported functionality or balance (primary outcomes), knee function, pain, falls, or quality of life.

RESULTS

Eight trials were included, involving 567 participants. The quantitative synthesis found a moderate to high significant effect of balance and proprioceptive trainings on self-reported functionality and balance after total knee replacement. The effects were maintained at mid-term in terms of balance alone. Conversely, preoperative training did not enhance outcomes after total hip arthroplasty.

SIGNIFICANCE

The synthesis showed that, in clinical terms, balance trainings are a convenient complement to conventional physiotherapy care to produce an impact on balance and functionality after knee replacement. If outcomes such as improvement in pain, knee range of movement, or patient quality of life are to be promoted, it would be advisable to explore alternative proposals specifically targeting these goals. Further research is needed to confirm or discard the current evidence ultimately, predominantly in terms of the effects on the hips and those yielded by preoperative interventions.

Pain sensitivity at rest and during muscle contraction in persons with rheumatoid arthritis: a substudy within the Physical Activity in Rheumatoid Arthritis 2010 study

Background

We aimed to explore pressure pain sensitivity and the function of segmental and plurisegmental exercise-induced hypoalgesia (EIH) in persons with rheumatoid arthritis (RA) compared with healthy control subjects (HC).

Methods

Forty-six participants with RA (43 female, 3 male) and 20 HC (16 female, 4 male) participated in the study. Pressure pain thresholds, suprathreshold pressure pain at rest, and segmental and plurisegmental EIH during standardised submaximal contractions were assessed by algometry. Assessments of EIH were made by performing algometry alternately at the contracting (30% of the individual maximum) right m. quadriceps and the resting left m. deltoideus.

Results

Participants with RA had higher sensitivity to pressure pain (RA, 318 kPa; HC, 487 kPa; p < 0.001), suprathreshold pressure pain 4/10 (RA, 433 kPa; HC, 638 kPa; p = 0.001) and suprathreshold pressure pain 7/10 (RA, 620 kPa; HC, 851 kPa; p = 0.002) than HC. Segmental EIH (RA, 0.99 vs 1.27; p < 0.001; HC, 0.89 vs 1.10; p = 0.016) and plurisegmental EIH (RA, 0.95 vs 1.36; p < 0.001; HC, 0.87 vs 1.31; p < 0.001) increased significantly during static muscle contraction in both groups alike (p > 0.05).

Conclusions

Our results indicate a generally increased pain sensitivity but normal function of EIH among persons with RA and offer one possible explanation for pain reduction observed in this group of patients following clinical exercise programmes.

Trial registration

ISRCTN registry, ISRCTN25539102. Retrospectively registered on 4 March 2011.

Assessment and manifestation of central sensitisation across different chronic pain conditions

Different neuroplastic processes can occur along the nociceptive pathways and may be important in the transition from acute to chronic pain and for diagnosis and development of optimal management strategies. The neuroplastic processes may result in gain (sensitisation) or loss (desensitisation) of function in relation to the incoming nociceptive signals. Such processes play important roles in chronic pain, and although the clinical manifestations differ across condition processes, they share some common mechanistic features. The fundamental understanding and quantitative assessment of particularly some of the central sensitisation mechanisms can be translated from preclinical studies into the clinic. The clinical perspectives are implementation of such novel information into diagnostics, mechanistic phenotyping, prevention, personalised treatment, and drug development. The aims of this paper are to introduce and discuss (1) some common fundamental central pain mechanisms, (2) how they may translate into the clinical signs and symptoms across different chronic pain conditions, (3) how to evaluate gain and loss of function using quantitative pain assessment tools, and (4) the implications for optimising prevention and management of pain. The chronic pain conditions selected for the paper are neuropathic pain in general, musculoskeletal pain (chronic low back pain and osteoarthritic pain in particular), and visceral pain (irritable bowel syndrome in particular). The translational mechanisms addressed are local and widespread sensitisation, central summation, and descending pain modulation.

Significance

Central sensitisation is an important manifestation involved in many different chronic pain conditions. Central sensitisation can be different to assess and evaluate as the manifestations vary from pain condition to pain condition. Understanding central sensitisation may promote better profiling and diagnosis of pain patients and development of new regimes for mechanism based therapy. Some of the mechanisms underlying central sensitisation can be translated from animals to humans providing new options in development of therapies and profiling drugs under development.

Ottawa Panel evidence-based clinical practice guidelines for therapeutic exercise in the management of hip osteoarthritis

Objectives:

The primary objective is to identify effective land-based therapeutic exercise interventions and provide evidence-based recommendations for managing hip osteoarthritis. A secondary objective is to develop an Ottawa Panel evidence-based clinical practice guideline for hip osteoarthritis.

Methods:

The search strategy and modified selection criteria from a Cochrane review were used. Studies included hip osteoarthritis patients in comparative controlled trials with therapeutic exercise interventions. An Expert Panel arrived at a Delphi survey consensus to endorse the recommendations. The Ottawa Panel hierarchical alphabetical grading system (A, B, C+, C, D, D+, or D-) considered the study design (level I: randomized controlled trial and level II: controlled clinical trial), statistical significance ( p < 0.5), and clinical importance (⩾15% improvement).

Results:

Four high-quality studies were included, which demonstrated that variations of strength training, stretching, and flexibility exercises are generally effective for improving the management of hip osteoarthritis. Strength training exercises displayed the greatest improvements for pain (Grade A), disability (Grades A and C+), physical function (Grade A), stiffness (Grade A), and range of motion (Grade A) within a short time period (8–24 weeks). Stretching also greatly improved physical function (Grade A), and flexibility exercises improved pain (Grade A), range of motion (Grade A), physical function (Grade A), and stiffness (Grade C+).

Conclusion:

The Ottawa Panel recommends land-based therapeutic exercise, notably strength training, for management of hip osteoarthritis in reducing pain, stiffness and self-reported disability, and improving physical function and range of motion.

Similar patient-reported outcomes and performance after total knee arthroplasty with or without patellar resurfacing

Background and purpose - Knee pain after total knee arthroplasty (TKA) is not uncommon. Patellar retention in TKA is one cause of postoperative knee pain, and may lead to secondary addition of a patellar component. Patellar resurfacing in TKA is controversial. Its use ranges from 2% to 90% worldwide. In this randomized study, we compared the outcome after patellar resurfacing and after no resurfacing. Patients and methods - We performed a prospective, randomized study of 74 patients with primary osteoarthritis who underwent a Triathlon CR TKA. The patients were randomized to either patellar resurfacing or no resurfacing. They filled out the VAS pain score and KOOS questionnaires preoperatively, and VAS pain, KOOS, and patient satisfaction 3, 12, and 72 months postoperatively. Physical performance tests were performed preoperatively and 3 months postoperatively. Results - We found similar scores for VAS pain, patient satisfaction, and KOOS 5 subscales at 3, 12, and 72 months postoperatively in the 2 groups. Physical performance tests 3 months postoperatively were also similar in the 2 groups. No secondary resurfacing was performed in the group with no resurfacing during the first 72 months Interpretation - Patellar resurfacing in primary Triathlon CR TKA is of no advantage regarding pain, physical performance, KOOS 5 subscales, or patient satisfaction compared to no resurfacing. None of the patients were reoperated with secondary addition of a patellar component within 6 years. According to these results, routine patellar resurfacing in primary Triathlon TKA appears to be unnecessary.

The efficacy of non-surgical treatment on pain and sensitization in patients with knee osteoarthritis: a pre-defined ancillary analysis from a randomized controlled trial

OBJECTIVE

To report the efficacy of a 3-month treatment program consisting of neuromuscular exercise, education, diet, insoles and pain medication (MEDIC-treatment) compared to usual care (two leaflets with information and treatment advice) in reducing pain-related measures and sensitization in patients with knee osteoarthritis (OA) not eligible for total knee replacement (TKR).

METHOD

A pre-defined ancillary analysis of the results at 3 months of a randomized controlled trial (RCT) of 100 patients randomized to MEDIC-treatment or usual care.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01535001). Outcomes were sensitization assessed at the knee, the lower leg and forearm using a handheld algometer, peak pain intensity in the previous 24 h, pain intensity after 30 min of walking, pain location and pattern, spreading of pain (a region-divided body chart) and the usage of pain medication.

RESULTS

The MEDIC group had larger improvements from baseline to 3 months in peak pain intensity (P = 0.02) and pain after 30 min of walking (P < 0.001) and in the number of body sites with pain (P = 0.04). There was no difference in the change in sensitization from baseline to 3 months between groups (P = 0.87), but sensitization decreased in both groups (P < 0.001).

CONCLUSION

A non-surgical treatment program is more efficacious in reducing pain-related measures than usual care, while both are equally efficacious in reducing sensitization, indicating that mechanisms other than pain sensitization contribute to the perceived pain. The patients did not have severe symptomatic knee OA and hence pain sensitization may not yet have developed into a clinically relevant parameter or subgroups with less sensitization may exist.

Altered Central Sensitization and Pain Modulation in the CNS in Chronic Joint Pain

Musculoskeletal pain disorders are the second largest contributor to global disability underlining the significance of effective treatments. However, treating chronic musculoskeletal pain, and chronic joint pain (osteoarthritis (OA)) in particular, is challenging as the underlying peripheral and central pain mechanisms are not fully understood, and safe and efficient analgesic drugs are not available. The pain associated with joint pain is highly individual, and features from radiological imaging have not demonstrated robust associations with the pain manifestations. In recent years, a variety of human quantitative pain assessment tools (quantitative sensory testing (QST)) have been developed providing new opportunities for profiling patients and reaching a greater understanding of the mechanisms involved in chronic joint pain. As joint pain is a complex interaction between many different pain mechanisms, available tools are important for patent profiling and providing the basic knowledge for development of new drugs and for developing pain management regimes.

Association of exercise therapy and reduction of pain sensitivity in patients with knee osteoarthritis: a randomized controlled trial

OBJECTIVE

Exercise has beneficial effects on pain in knee osteoarthritis (OA), yet the underlying mechanisms are unclear. The purpose of this study was to investigate the effects of exercise on pressure-pain sensitivity in patients with knee OA.

METHODS

In a randomized controlled trial, participants were assigned to 12 weeks of supervised exercise therapy (ET; 36 sessions) or a no attention control group (CG). Pressure-pain sensitivity was assessed by cuff pressure algometry on the calf of the most symptomatic leg. The coprimary outcomes were pressure-pain thresholds (PPTs) and cumulated visual analog scale pain scores during constant pressure for 6 minutes at 125% of the PPT as a measure of temporal summation (TS) of pressure-pain. Secondary outcomes included self-reported pain using the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Analyses were based on the "per-protocol" population (participants following the protocol).

RESULTS

Sixty participants were randomized (31 in ET group, 29 in CG), and the per-protocol population included 48 participants (25 in ET group, 23 in CG). At followup, mean group differences in the change from baseline were 3.1 kPa (95% confidence interval [95% CI] 0.2, 6.0; P = 0.038) for the PPT, 2,608 mm × seconds (95% CI 458, 4,758; P = 0.019) for TS, and 6.8 points (95% CI 1.2, 12.4; P = 0.018) for KOOS pain, all in favor of ET.

CONCLUSION

Pressure-pain sensitivity, TS, and self-reported pain are reduced among patients completing a 12-week supervised exercise program compared to a no attention CG. These results demonstrate beneficial effects of exercise on basic pain mechanisms and further exploration may provide a basis for optimized treatment.